Weak grid integrated solar photovoltaic-based distributed generation system proficient in supplying VAR requirement with current restriction

This study presents a grid interactive solar photovoltaic (PV) system proficient with low voltage ride through capability. When the supply voltage drops more than 10%, the solar PV system remains connected and continues to supply the active power to the loads as well as to the grid. Along with the active power supply, the solar PV array system supplies the reactive power for stabilising the system. Due to the supply of both the active and reactive powers, there is a chance for a grid fed inverter (GFI) current to exceed the maximum current limit. It may result in the tripping of inverter protection. Therefore, a current limiting logic is incorporated to keep the inverter current within the safe limit. The unbalanced voltages are responsible for circulation of negative sequence currents in the system. As the prime aim of the present work deals with the supply of positive sequence currents to the grid, it is required to estimate the positive and negative sequence voltages separately. Intending the estimation of sequence voltages from unbalanced supply voltages, a frequency adaptive higher order complex filter (FAHOCF) is used. A MATLAB model of grid interactive solar PV array is developed and simulated results are verified with test results.